#include<signal.h>

typedef void (* SigFunc)(int);

SigFunc signal(int signo, SigFunc func)
{
	struct sigaction act, oact;

	act.sa_handler = func;
	sigemptyset(&act.sa_mask);
	act.sa_flags = 0;

	if(signo == SIGALRM) {
#ifdef SA_INTERRUPT
		act.sa_flags |= SA_INTERRUPT;
#endif
	} else {
#ifdef SA_RESTART
		act.sa_flags |= SA_RESTART;
#endif
	}

	if(sigaction(signo, &act, &oact) < 0)
		return SIG_ERR;
	return oact.sa_handler;
}
